What does a reviewer do during peer-review?

a. focus on mistakes in spelling.

b. change data to support results.

c. check for mistakes and bias.

d. repeat the experiments in the article.

A and C. If it's a peer-review you are most likely going over it and checking everything is correct, that there is nothing wrong you wouldn't repeat the experiments unless the instructions for them were to create a experiment and give it to someone to repeat/do. You wouldn't change the data they would. So in a way it is also B.

The correct answer is a. when they started making tools that will them in cultivating lands, they could raise crops and that made them attached to one place for a longer period of time. after that, they started domesticating animals and building their own permanent settlements that resemble the ones we have today.

Americans often speak of their country as one of several large regions.  these regions are cultural units rather than governmental units --  formed by history and geography and shaped by the economics, literature and folkways that all the parts of a region share. what makes one region different from another? a region's multicultural heritage as well as distinct demographic characteristics like age and occupation make regions different and special. within several regions, language is used differently and there are strong dialects. there are also differences in outlook and attitude based on geography.